fix(gatsby): stale node manifests

packages/gatsby/src/utils/page-data.ts

@@ -182,6 +182,9 @@ export function isFlushEnqueued(): boolean {
   return isFlushPending
 }
 
+let staleNodeManifests = false
+const maxManifestIdsToLog = 50
+
 type IDataTask =
   | {
       type: "page"
@@ -208,6 +211,7 @@ export async function flush(parentSpan?: Span): Promise<void> {
     queries,
     slices,
     slicesByTemplate,
+    nodeManifests,
   } = store.getState()
   const isBuild = program?._?.[0] !== `develop`
 
@@ -221,6 +225,25 @@ export async function flush(parentSpan?: Span): Promise<void> {
     // We use this manifestId to determine if the page data is up to date when routing. Here we create a map of "pagePath": "manifestId" while processing and writing node manifest files.
     // We only do this when there are pending page-data writes because otherwise we could flush pending createNodeManifest calls before page-data.json files are written. Which means those page-data files wouldn't have the corresponding manifest id's written to them.
     nodeManifestPagePathMap = await processNodeManifests()
+  } else if (nodeManifests.length > 0 && staleNodeManifests) {
+    staleNodeManifests = false
+
+    reporter.warn(
+      `[gatsby] node manifests were created but no page-data.json files were written, so manifest ID's were not added to page-data.json files. This may be a bug or it may be due to a source plugin creating a node manifest for a node that did not change. Node manifest IDs: ${nodeManifests
+        .map(n => n.manifestId)
+        .slice(0, maxManifestIdsToLog)
+        .join(`,`)}${
+        nodeManifests.length > maxManifestIdsToLog
+          ? ` There were ${
+              nodeManifests.length - maxManifestIdsToLog
+            } additional ID's that were not logged due to output length.`
+          : ``
+      }`
+    )
+
+    nodeManifestPagePathMap = await processNodeManifests()
+  } else if (nodeManifests.length > 0) {
+    staleNodeManifests = true
   }
 
   if (pagePaths.size > 0 || sliceNames.size > 0) {